1. Field of the Invention
The present invention relates generally to a stapler device and more particularly, to a stapler device for stapling sheets outputted from copiers or printers.
2. Description of the Related Art
A variety of finishers have generally been provided which operate to sort image-copied sheets outputted from the copier or printer into a desired number of sheet sets or perform a stapling operation. Of the prior-art stapler devices, the conventional type has an arrangement wherein a head section for driving a staple and an anvil section for receiving and bending the staple are fixed to a given position, thus binding a stack of sheets only at one place. More recently, however, with automation and diversification of the sheet finishing operation, the performance of the stapling operation is also diversified. Thus, a demand exists for an ability to selectively bind a stack of sheets at any one or more than one of binding positions such as a leading edge, a trailing edge and a center of the sheet stack.
For binding sheets at plural positions, a stapler unit (the head section and anvil section) must be moved in a sheet-width direction. A coupling member generally unifies the head section and the anvil section so as to ensure the alignment thereof. Because of the existence of the coupling member, however, the sheet stack can be transported into or out of a stapling section only after the coupling member is retreated. This results in an increased processing time, which lowers the productivity of copies.
Besides, a long coupling member is required for driving the staple into the center of the sheet stack. This results in low accuracy of positioning and an increased size of the stapler device.
In this connection, the present inventors have proposed in Japanese Unexamined Patent Publication No.9-255220 a stapler device wherein the head section and the anvil section are independent from each other thereby to dispense with the coupling member. In this device, the head section and the anvil section are guided by a support shaft, respectively. Unfortunately, at the occurrence of trouble such as caused by staple clogging in the head section or the anvil section, the head section or the anvil section along with the support shaft must be removed from the sorter for maintenance work which is quite cumbersome.